The present invention relates generally to the manufacture of semiconductor components. More particularly, the present invention is directed to a method for generating apertured openings or trenches in layers or substrates composed of n-silicon as used in the manufacture of semiconductor components, particularly LSI semiconductor circuits, through masked etching.
One of the most important materials in the creation of microelectronic components is silicon. As such, silicon requires more and more designational and specific methods for surface structuring. One of the more technically difficult areas in the manufacture of semiconductor components is the generation of trenches, or, respectively, holes in the silicon surface.
Heretofore, chemical etching methods or plasma etching methods were typically used for generating, in the silicon surface, hole-shaped or trench-shaped structures. When these methods are utilized, the following difficulties arise:
(a) using isotropic chemical etching (acidic) results in under-etchings that greatly limit the possible etching geometries - this is illustrated in FIG. 1, the under etchings being represented by 10;
(b) when anisotropic chemical etching (alkaline) is used, the plurality of realizable etching geometries is highly limited by the crystal faces - see FIG. 2, wherein the crystal faces are represented by 100 and 111; and
(c) in plasma etching, as may be derived, for example, from a report by Morie et al in IEEE Electron Device Letters, Volume EDL-4, No. 11 (November 1983), pages 411 through 414, for the creation of the trench cells of Mbit memories dimensions below 1 um as well as depth-to-width ratios T/B greater than 10 in holes can only be achieved with great difficulty (see FIG. 3). The rectangular cross-section in Morie is highly dependent on the gas pressure of the reaction gas (tri-fluoro bromomethane).
Accordingly, there is a need for an improved method for generating openings or trenches in silicon surfaces to manufacture semiconductor components.